diff --git a/lib/syntax_suggest/core_ext.rb b/lib/syntax_suggest/core_ext.rb
index f2fbc7a..e0fd62b 100644
--- a/lib/syntax_suggest/core_ext.rb
+++ b/lib/syntax_suggest/core_ext.rb
@@ -45,6 +45,8 @@ def detailed_message(highlight: true, syntax_suggest: true, **kwargs)
             )
             annotation = io.string
 
+            annotation += "\n" unless annotation.end_with?("\n")
+
             annotation + message
           else
             message